Our application (C#) is using ExchangeVersion.Exchange2010_SP2 (EWS 1.2) on Exchange 2010. Now we want upgrade to Exchange 2013.
Are there some critical points (update EWS dll, ...?) to take care before migration or there should not be any issues through the Version change?
All mailboxes will be migrated to.
You should be able to converse between your Exchange2010_SP2 app the new E2013 server without difficulty. The only thing I can recall to watch out for depends on whether you are using subscriptions for Push or Streaming Notifications. (I assume Pull also, but I've never dealt with those.) Because the subscriptions are maintained on the MB servers instead of the CAS's as they were in E2010, there are some HTTP headers you need to manage. If you need more details, let me know, but hopefully you don't! :-)
ExchangeVersion.Exchange2010_SP2toExchangeVersion.Exchange2013in your code? I recommend not doing that (just talk to your Exchange2013 as if it is still 2010SP2) until you have time to properly test your entire application. Some calls to the server may have syntax changes. – Jan Doggen